import com.fasterxml.jackson.databind.ObjectMapper;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

class User{
    public String username;
    public String password;
}
@WebServlet("/json")
public class JsonServlet extends HttpServlet {
    //使用jackson最核心的对象就是ObjectMapper
    //通过这个对象就可以把json字符串解析成java对象，也可以把一个java对象转成一个json格式字符换
    private ObjectMapper objectMapper=new ObjectMapper();

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //通过post请求的body传递一个json格式的字符串
        User user=objectMapper.readValue(req.getInputStream(),User.class);
        System.out.println("username="+user.username+",password="+ user.password);
        resp.getWriter().write("ok");
    }
}
